Humidifying apparatus

ABSTRACT

Humidifying apparatus includes a housing defining a water reservoir, and a water tank mounted on the housing for supplying water to the reservoir. An air flow is conveyed over water stored in the reservoir and emitted from the apparatus. The water stored in the reservoir is irradiated by ultraviolet radiation and atomized by a transducer to humidify the air flow passing over the reservoir. A flow of water entering the reservoir is guided adjacent to, and preferably along, the ultraviolet radiation generator.

REFERENCE TO RELATED APPLICATIONS

This application claims the priority of United Kingdom Application no.1203909.5, filed Mar. 6, 2012, the entire contents of which areincorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to a humidifying apparatus. In a preferredembodiment, the present invention provides a humidifying apparatus forgenerating a flow of moist air and a flow of air for dispersing themoist air within a domestic environment, such as a room, office or thelike.

BACKGROUND OF THE INVENTION

Domestic humidifying apparatus is generally in the form of a portableappliance having a casing comprising a water tank for storing a volumeof water, and a fan for creating a flow of air through an air duct ofthe casing. The stored water is conveyed, usually under gravity, to anatomizing device for producing water droplets from the received water.This device may be in the form of a heater or a high frequency vibratingdevice, such as a transducer. The water droplets enter the flow of airpassing through the air duct, resulting in the emission of a mist intothe environment. The appliance may include a sensor for detecting therelative humidity of the air in the environment. The sensor outputs asignal indicative of the detected relative humidity to a drive circuit,which controls the transducer to maintain the relative humidity of theair in the environment around a desired level. Typically, the actuationof the transducer is stopped when the detected relative humidity isaround 5% higher than the desired level, and is restarted when thedetected relative humidity is around 5% lower than the desired level.

It is known to provide an ultraviolet (UV) lamp or other UV radiationgenerator to sterilize water that is conveyed to the atomizing device.For example, U.S. Pat. No. 5,859,952 describes a humidifier in which thewater supplied from a tank is conveyed through a sterilizing chamberbefore being conveyed by a pipe to a chamber containing an ultrasonicatomizer. The sterilizing chamber has a UV transparent window beneathwhich a UV lamp is located to irradiate water as it passes through thesterilizing chamber. U.S. Pat. No. 7,540,474 describes a humidifier inwhich the water tank includes a UV transparent tube for conveying waterto an outlet of the tank, and a main body upon which the tank is mountedincludes a UV lamp which irradiates water as it passes through the tubeto the outlet.

SUMMARY OF THE INVENTION

In a first aspect, the present invention provides a method of generatinga humid air flow, comprising the steps of irradiating water stored in areservoir with ultraviolet radiation, conveying an air flow over waterstored in the reservoir, and atomizing water stored in the reservoir tohumidify the air flow, wherein water stored in the reservoir is agitatedfor a period of time during the irradiation of water stored in thereservoir and which is prior to the atomization of water stored in thereservoir.

The invention can enable a humidifying apparatus to have a compactappearance through both irradiating and atomizing water stored within acommon reservoir. To enable the number of bacteria within the storedwater to be reduced before the atomization of the stored watercommences, there is a delay between the irradiation of the stored waterwith UV radiation and the commencement of the atomization of the storedwater to humidify the air flow conveyed over the reservoir. During theperiod of time in which the irradiation is performed prior to theatomization of stored water, the water stored in the reservoir isagitated to generate a flow or swirl of water within the reservoir, andwhich conveys water through the UV radiation emitted into the reservoir.This can increase the volume of the stored water which is irradiatedwith UV radiation prior to the atomization of the stored water, and thusincrease the rate of reduction of the number of bacteria within thewater stored in the reservoir.

The duration of the period of time for which the stored water isirradiated with UV radiation prior to the commencement of theatomization of stored water will depend, inter alia, on the volume ofthe reservoir and the desired reduction in the number of bacteria withinthe stored water. For example, the duration of this period of time maybe in the range from 10 to 300 seconds to achieve an appropriatereduction in the number of bacteria within the maximum volume of waterwhich can be stored in the reservoir. The duration may be reduceddepending on the length of time which has elapsed since the humidifyingapparatus was previously operated. Water is preferably supplied to thereservoir from a tank which is removably mountable on a base or housingin which the reservoir is located. The water tank and the housing maytogether provide a body of the humidifying apparatus. The duration ofthe period of time for which water is irradiated prior to atomizationmay be set automatically to a maximum value when the water tank isremoved from the housing, for example for replenishment.

The removal of the water tank from the housing may be detected by aproximity sensor located on the housing, and which interacts with amagnet or other feature located on the water tank to detect the presenceor absence of the water tank on the housing. Both the agitation and theirradiation of stored water are preferably suspended if the water tankis removed from the housing.

The atomization and the irradiation of the stored water may also besuspended depending on the volume of water within the reservoir. Forexample, a level detector may be located in the reservoir for outputtinga signal indicative of a low level of water in the reservoir, inresponse to which the atomization and the irradiation of the storedwater are suspended.

The atomization of water stored in the reservoir may be suspended whenthe humidity of the air flow conveyed to the reservoir is above a firstlevel, and resumed when the humidity of the air flow conveyed to thereservoir is below a second level lower than the first value. The firstand second levels may be set according to a humidity level selected by auser either using a user interface located on the apparatus or using aremote control, and may be, for example, any relative humidity withinthe range from 30 to 80% at 20° C. For example, the first level may be1% at 20° C. higher than the selected level, whereas the second levelmay be 1% at 20° C. lower than the selected level. Both the agitationand the irradiation of the stored water may be continued as the detectedhumidity falls from the first level to the second level. A sensor fordetecting the humidity of the air flow conveyed to the reservoir may beprovided at any convenient location upstream of the reservoir. Forexample, the sensor may be located immediately downstream from an airinlet of the apparatus.

The irradiation of the stored water with UV radiation may be performedby a UV lamp or other UV radiation generator. The UV radiation generatormay be located behind a window which partially defines the volume of thereservoir. Alternatively, the UV radiation generator may be located inthe reservoir. For example, the UV radiation generator may comprise a UVtransparent tube at least partially located in the reservoir so thatagitated water moves along or around the outer surface of the tube. Thereservoir may comprise a reflective surface for directing the UVradiation to one or more regions of the reservoir. This surface maydefine at least part of the reservoir, or it may be located above orwithin the reservoir. For example, at least part of one wall of thereservoir may be formed from, or coated with, reflective material. Thereflective surface may extend around the tube. This can allow watersurrounding the tube to be irradiated by UV radiation, therebyincreasing the volume of water which can be irradiated in comparison toa system where a UV radiation generator is located adjacent to a windowprovided on one side of the reservoir. As the air flow is conveyed overwater stored in the reservoir, a swirl of water is preferably generatedwithin the stored water in such a direction as to generate a flow ofwater adjacent to, and preferably along, the tube.

Water is preferably supplied to the reservoir from an inlet locatedadjacent to the location at which the stored water is irradiated. Atleast one wall, baffle or other fluid guiding means may be provided inthe reservoir to guide a flow of water entering the reservoir from thewater tank adjacent to, and preferably along, the UV transparent tube orwindow behind which the UV radiation generator is located. As a result,water entering the reservoir from the tank—to replenish the reservoirduring water atomization or when the reservoir is refilled—is irradiatedwith UV radiation before it is atomized. The agitation of the storedwater preferably promotes the movement of water along and/or around theUV radiation generator.

The agitation of the water stored in the reservoir may be performed inone or more of a number of different ways. For example, the stored watermay be agitated mechanically by an agitating device, such as a stirreror other moveable device, provided in the reservoir for movementrelative to the reservoir to agitate the stored water. As anotherexample, the water stored in the reservoir may be agitated sonically bya transducer located in the reservoir. As a further example, the waterstored in the reservoir may be agitated by aerating the stored water,for example by pumping air over or through the stored water. This pumpedair may be diverted from the air flow conveyed over the stored water, orit may be generated separately from that air flow. As yet anotherexample, the stored water may be agitated through oscillation orvibration of one or more of the walls of the reservoir.

In a preferred embodiment, the stored water is agitated by the air flowconveyed over the water stored in the reservoir, and so in a secondaspect, the present invention provides a method of generating a humidair flow, comprising the steps of (i) irradiating water stored in areservoir with ultraviolet radiation, (ii) conveying an air flow overwater stored in the reservoir, and (iii) atomizing water stored in thereservoir to humidify the air flow, wherein steps (i) and (ii) areperformed simultaneously for a period of time prior to step (iii).

The air flow is preferably conveyed into or over the reservoir above themaximum level to which water may be stored in the reservoir. Forexample, if the maximum water level is at the upper periphery of thereservoir, then air is preferably conveyed over the upper periphery ofthe reservoir. If the maximum water level is below the upper peripheryof the reservoir, then air may be conveyed into the reservoir betweenthe upper periphery of the reservoir and the maximum water level.

The air flow may be conveyed downwardly towards the surface of thestored water. The air flow may be emitted over the water in thereservoir from a first location, and the water stored in the reservoirmay be irradiated at a second location proximate to the first locationso that the agitation is initiated close to the irradiation device tomaximise the rate at which the stored water moves relative to theirradiation device. The humidifying apparatus may comprise an inlet ductfor conveying the air flow to the reservoir, and an outlet duct forconveying a humidified air flow away from the reservoir. An outlet portof the inlet duct may be shaped to emit the air flow in such a directionand/or with such a profile as to generate a swirling movement of thewater stored in the reservoir.

The atomization is preferably conducted at a third location within thereservoir, with the second location being disposed between the first andthird locations. This can prevent the air flow entering the reservoirfrom blowing stored water away from the location at which atomization isperformed. The atomization may be performed by a heater but in apreferred embodiment the atomization is performed by a vibratingtransducer. The transducer may be vibrated at one of a number ofdifferent modes. The water may be atomized by vibrating the transducerin an atomization mode, and agitated, with no or little atomizationthereof, by vibrating the transducer in an agitation mode. In theatomization mode, the transducer is vibrated at a first frequency f₁,which may be in the range from 1 to 2 MHz. In the agitation mode, thetransducer may be vibrated at a second frequency f₂, where f₁>f₂>0.Alternatively, in the agitation mode the transducer may be vibrated atthe first frequency f₁, but with reduced amplitude. Additionally, oralternatively, the duty cycle of the signals output to the transducermay be varied between the atomization and agitation modes.

The agitation of the stored water may be performed simultaneously by thetransducer and by the air flow conveyed to the reservoir. Alternatively,the agitation of the stored water may be performed by one of thetransducer and the air flow. Therefore, in a third aspect the presentinvention provides a method of generating a humid air flow, comprisingthe steps of irradiating water stored in a reservoir with ultravioletradiation, conveying an air flow over water stored in the reservoir, andvibrating a transducer in an atomization mode to atomize water stored inthe reservoir to humidify the air flow, wherein, before the water isatomized, the transducer is vibrated in an agitation mode to agitatewater stored in the reservoir for a period of time during which storedwater is irradiated with ultraviolet radiation.

When atomization is not required, for example when the detected humidityis above the first level, the mode of vibration of the transducer may bechanged. This mode of operation may be the same as, or different from,the agitation mode. For example, the vibration of the transducer may besuspended when atomization is not required.

A threshold inhibitor, such as a polyphosphate, may be introduced to thestored water to inhibit the precipitation of limescale on the surfacesof the atomization device and the UV transparent tube or window whichare in contact with stored water. The polyphosphate forms a thin coatingon the aforementioned surfaces which prevents precipitation of limescalethereon. Where the atomization is performed by a transducer, thepresence of this coating has been found to increase significantly thelifetime of the transducer. An amount of polyphosphate may be storedwithin a chamber located between the water tank and the reservoir andthrough which the water passes to the reservoir so that thepolyphosphate is added to the water entering the reservoir. As waterpasses over the polyphosphate stored within the chamber, thepolyphosphate gradually dissolves, and so a barrier may be providedupstream from the reservoir for preventing relatively large amounts ofpolyphosphate from entering the reservoir and becoming deposited on thetransducer. This barrier may be in the form of a mesh located betweenthe chamber or the reservoir, or in the form of a wall located in thechamber or between the bottom wall of the chamber and an outlet throughwhich water is exhausted from the chamber. The outlet may comprise aplurality of apertures formed in a side wall of the chamber. The chambermay be located immediately beneath the water tank so that water poursinto the chamber when the water tank is mounted on the reservoir. Anupper wall of the chamber may comprise an inlet through which waterenters the chamber from the water tank, and through which air isdisplaced as the chamber fills with water. The outlet of the chamber ispreferably located beneath the inlet of the chamber.

In a fourth aspect the present invention provides humidifying apparatuscomprising a housing comprising a water reservoir, a water tank mountedon the housing for supplying water to the reservoir, air flow generatingmeans for generating an air flow over water in the reservoir, an airoutlet for emitting at least part of the air flow, atomizing means foratomizing water in the reservoir, irradiating means for irradiatingwater in the reservoir with ultraviolet radiation, and a chamber forconveying water from the water tank to the reservoir, the chambercontaining a threshold inhibitor.

In a fifth aspect the present invention provides humidifying apparatuscomprising a housing comprising a water reservoir, a water tank mountedon the housing for supplying water to the reservoir, air flow generatingmeans for generating an air flow over water in the reservoir, an airoutlet for emitting at least part of the air flow, atomizing means foratomizing water in the reservoir, irradiating means for irradiatingwater in the reservoir with ultraviolet radiation, and guide means forguiding a flow of water entering the reservoir adjacent to theirradiating means.

The present invention extends to humidifying apparatus for performingany of the above methods for generating a humid air flow.

In a sixth aspect, the present invention provides humidifying apparatuscomprising a housing comprising a water reservoir, air flow generatingmeans for generating an air flow over water in the reservoir, an airoutlet for emitting at least part of the air flow, atomizing means foratomizing water in the reservoir, irradiating means for irradiatingwater in the reservoir with ultraviolet radiation, and control means forcontrolling the actuation of the air flow generating means, theatomizing means and the irradiating means, wherein the control means isconfigured to actuate the air flow generating means and the irradiatingmeans for a period of time prior to the actuation of the atomizingmeans.

As mentioned above, the atomizing means may comprise at least onetransducer, and so the control means may be configured to actuatevibration of the transducer in an atomization mode, and to actuatevibration of the transducer in an agitation mode, different from theatomization mode, during said period of time to agitate the storedwater. Therefore, in a seventh aspect the present invention provideshumidifying apparatus comprising a housing comprising a water reservoir,air flow generating means for generating an air flow over water in thereservoir, an air outlet for emitting at least part of the air flow,atomizing means for atomizing water in the reservoir, the atomizingmeans comprising a transducer, irradiating means for irradiating waterin the reservoir with ultraviolet radiation, and control means forcontrolling the actuation of the air flow generating means and theirradiating means, and for controlling the frequency of vibration of thetransducer, wherein the control means is configured to actuate vibrationof the transducer in an atomization mode to atomize water, and toactuate simultaneously the irradiating means and vibration of thetransducer in an agitation mode to agitate water in the reservoir for aperiod of time prior to the actuation of the vibration of the transducerin the atomization mode.

The control means may comprise one or more control circuits or drivecircuits of the humidifying apparatus, and which may each comprise aseparate processor. For example, a drive circuit may be locatedproximate to the transducer, and which is connected to a central drivecircuit for operating the air flow generating means and the irradiatingmeans. The air flow generating means preferably comprises an impellerand a motor for rotating the impeller to generate the air flow. Theirradiating means preferably comprises a UV radiation generator, such asa UV lamp.

The air outlet may be located on the housing. Alternatively, the airoutlet may be located on a nozzle mounted on the housing. The nozzle ispreferably annular in shape, and extends about a bore through which airfrom outside the humidifying apparatus is drawn by air emitted from theair outlet. The air outlet may be located in a front end of the nozzle.The air outlet may comprise a plurality of apertures each for emitting arespective humid air stream, and each aperture may be located on arespective side of the bore. Alternatively, the nozzle may comprise asingle air outlet extending about the bore. The nozzle may comprise anair inlet for receiving the humid air flow, and an interior passageextending about the bore for conveying the air flow to the, or each, airoutlet. The interior passage may surround the bore of the nozzle.

The nozzle may be arranged to emit both the humid air flow, and aseparate air flow for conveying the humid air flow away from thehumidifying apparatus. This can enable the humid air flow to beexperienced rapidly at a distance from the humidifying apparatus. Thisseparate air flow may be generated by the air flow generating meanswhich generates the air flow over the reservoir. For example, thehousing may comprise a first air passageway for conveying the separateair flow to the nozzle and a second air passageway for conveying thehumid air flow to the nozzle. This second air passageway may be definedby the inlet and outlet ducts which convey air to and from thereservoir. The first air passageway preferably extends from an air inletof the housing to a first air inlet of the nozzle. The second airpassageway may be arranged to receive air directly from the air inlet ofthe housing. Alternatively, the second air passageway may be arranged toreceive air from the first air passageway. In this case, the junctionbetween the air passageways may be located downstream or upstream fromthe air flow generating means. An advantage of locating the junctiondownstream from the air flow generating means is that the flowgenerating means may comprise a single impeller and a motor forgenerating an air flow which is divided into two air flows downstreamfrom the impeller.

The nozzle may thus comprise at least one first air inlet, at least onefirst air outlet, a first interior passage for conveying air from saidat least one first air inlet to said at least one first air outlet, atleast one second air inlet, at least one second air outlet, and a secondinterior passage for conveying air from said at least one second airinlet to said at least one second air outlet, with the nozzle defining abore through which air from outside the humidifying apparatus is drawnby air emitted from the nozzle.

In an eighth aspect the present invention provides humidifying apparatuscomprising a nozzle comprising at least one first air inlet, at leastone first air outlet, a first interior passage for conveying air fromsaid at least one first air inlet to said at least one first air outlet,at least one second air inlet, at least one second air outlet, and asecond interior passage for conveying air from said at least one secondair inlet to said at least one second air outlet, the nozzle defining abore through which air from outside the humidifying apparatus is drawnby air emitted from the nozzle, and a body on which the nozzle ismounted, the body comprising air flow generating means for generating afirst air flow through the first interior passage and a second air flowthrough the second interior passage, a water reservoir, a first airpassageway for conveying the first air flow to the at least one firstair inlet, a second air passageway for conveying the second air flowover water in the reservoir to the at least one second air inlet,atomizing means for atomizing water in the reservoir to increase thehumidity of the second air flow, irradiating means for irradiating waterin the reservoir with ultraviolet radiation, and control means forcontrolling the actuation of the air flow generating means, theatomizing means and the irradiating means, wherein the control means isconfigured to actuate the air flow generating means and the irradiatingmeans for a period of time prior to the actuation of the atomizingmeans.

The nozzle may thus be arranged to emit both the moistened second airflow and the first air flow which carries the moistened air flow intothe environment. The moistened second air flow can be emitted from oneor more different air outlets of the nozzle. These air outlets may bepositioned, for example, about the bore of the nozzle to allow themoistened air flow to be dispersed relatively evenly within the firstair flow.

Preferably, the first air flow is emitted at a first air flow rate andthe second air flow is emitted at a second air flow rate which is lowerthan the first air flow rate. The first air flow rate may be a variableair flow rate, and so the second air flow rate may vary with the firstair flow rate.

The first air outlet(s) are preferably located behind the second airoutlet(s) so that the second air flow is conveyed away from the nozzlewithin the first air flow. Each interior passage is preferably annular.The two interior passages of the nozzle may be defined by respectivecomponents of the nozzle, which may be connected together duringassembly. Alternatively, the interior passages of the nozzle may beseparated by a dividing wall or other partitioning member locatedbetween inner and outer walls of the nozzle. As mentioned above, thefirst interior passage is preferably isolated from the second interiorpassage, but a relatively small amount of air may be bled from the firstinterior passage to the second interior passage to urge the second airflow through the second air outlet(s) of the nozzle.

As the flow rate of the first air flow is preferably greater than theflow rate of the second air flow, the volume of the first interiorpassage of the nozzle is preferably greater than the volume of thesecond interior passage of the nozzle.

The nozzle may comprise a single first air outlet, which preferablyextends at least partially about the bore of the nozzle, and ispreferably centred on the axis of the bore. Alternatively, the nozzlemay comprise a plurality of first air outlets which are arranged aboutthe bore of the nozzle. For example, the first air outlets may belocated on opposite sides of the bore. The first air outlet(s) arepreferably arranged to emit air through at least a front part of thebore. The first air outlet(s) may be arranged to emit air over a surfacedefining part of the bore to maximise the volume of air which is drawnthrough the bore by the air emitted from the first air outlet(s).Alternatively, the first air outlet(s) may be arranged to emit the airflow from an end surface of the nozzle.

The second air outlet(s) of the nozzle may be arranged to emit thesecond air flow over this surface of the nozzle. Alternatively, thesecond air outlet(s) may be located in a front end of the nozzle, andarranged to emit air away from the surfaces of the nozzle. The first airoutlet(s) may therefore be located adjacent to the second air outlet(s).The nozzle may comprise a single second air outlet, which may extend atleast partially about the axis of the nozzle. Alternatively, the nozzlemay comprise a plurality of second air outlets, which may be arrangedabout the front end of the nozzle. For example, the second air outletsmay be located on opposite sides of the front end of the nozzle. Each ofthe plurality of air outlets may comprise one or more apertures, forexample, a slot, a plurality of linearly aligned slots, or a pluralityof apertures. The first air outlets may extend parallel to the secondair outlets.

As mentioned above, the body may comprise a removable water tank forsupplying water to the reservoir. To provide the body with a compactappearance, the water tank preferably extends about the flow generatingmeans. In a preferred embodiment, the water tank surrounds the flowgenerating means. The water tank may surround at least part of the firstair passageway, and at least part of the second air passageway. The bodymay comprise a base comprising an air inlet through which air enters thehumidifying apparatus, and the water tank may be mounted on the base.Preferably, the base and the water tank each have a cylindrical outersurface, and the outer surfaces of the base and the water tank havesubstantially the same radius. This can further contribute towards thecompact appearance of the humidifying apparatus.

The nozzle may be mounted on the body so that the water tank surrounds alower section of the interior passages of the nozzle. For example, thewater tank may have an upper wall which is upwardly curved or concave inshape, and the nozzle may be mounted centrally on the water tank so thatthe upper wall extends around a lower part of the nozzle. This can allowthe humidifying apparatus to have a compact appearance, and can allowthe capacity of the water tank to be maximised.

The body may comprise means for releasably retaining the nozzle on thebody. For example, the body may comprise a detent which is locatable atleast partially within a recess located on the nozzle to retain thenozzle on the water tank. The body may comprise a catch which isoperable to move the detent away from the recess to release the nozzlefrom the body. This can allow the nozzle to be removed from the bodybefore the water tank is removed from the base, for example to refillthe water tank. The catch may be moveable between a first position and asecond position to move the detent away from the recess. The body maycomprise means for retaining the catch in the second position until thenozzle is replaced on the body. For example, the body may comprise awedge, hook or other profiled member for retaining the catch in thesecond position.

The water tank may comprise a handle which is moveable between a stowedposition and a deployed position to facilitate the removal of the watertank from the base. The water tank may comprise a spring or otherresilient element for urging the handle towards the deployed position.As the nozzle is replaced on the body, the nozzle may engage the handleto move the handle, against the biasing force of the resilient element,towards its first position. As the handle moves towards the stowedposition, the handle may engage the catch to urge the catch away fromthe wedge to release the catch from its second position. The detent ispreferably biased towards a deployed position for retaining the nozzle.The release of the catch from the second position can allow the detentto move automatically to its deployed position.

Features described above in connection with the first aspect of theinvention are equally applicable to each of the second to eighth aspectsof the invention, and vice versa.

BRIEF DESCRIPTION OF THE INVENTION

An embodiment of the present invention will now be described, by way ofexample only, with reference to the accompanying drawings, in which:

FIG. 1 is a front view of a humidifying apparatus;

FIG. 2 is a side view of the humidifying apparatus;

FIG. 3 is a rear view of the humidifying apparatus;

FIG. 4( a) is a side sectional view taken along line A-A in FIG. 1, withthe nozzle of the humidifying apparatus retained on the body, and FIG.4( b) is a similar view to FIG. 4( a) but with the nozzle released fromthe body;

FIG. 5( a) is a top sectional view taken along line B-B in FIG. 1, andFIG. 5( b) is a close-up of area P indicated in FIG. 5( a);

FIG. 6( a) is a perspective view, from above, of the base of thehumidifying apparatus with an outer wall of the base partially removed,and FIG. 6( b) is a similar view to FIG. 6( a) following a partialrotation of the base;

FIG. 7( a) is a perspective rear view, from above, of the water tankmounted on the base, with the handle in a deployed position, and FIG. 7(b) is a close-up of area R indicated in FIG. 7( a);

FIG. 8 is a top sectional view taken along line D-D in FIG. 4( a);

FIG. 9 is a sectional view take along line F-F in FIG. 8;

FIG. 10 is a rear perspective view, from below, of the nozzle;

FIG. 11 is a top sectional view taken along line E-E in FIG. 4( a);

FIG. 12( a) is a front sectional view taken along line C-C in FIG. 2,with the nozzle of the humidifying apparatus retained on the body, andFIG. 12( b) is a similar view to FIG. 12( a) but with the nozzlereleased from the body;

FIG. 13 is a schematic illustration of a control system of thehumidifying apparatus; and

FIG. 14 is a flow diagram illustrating steps in the operation of thehumidifying apparatus.

DETAILED DESCRIPTION OF THE INVENTION

FIGS. 1 to 3 are external views of a fan assembly. In this example, thefan assembly is in the form of a humidifying apparatus 10. In overview,the humidifying apparatus 10 comprises a body 12 comprising an air inletthrough which air enters the humidifying apparatus 10, and a nozzle 14in the form of an annular casing mounted on the body 12, and whichcomprises a plurality of air outlets for emitting air from thehumidifying apparatus 10.

The nozzle 14 is arranged to emit two different air flows. The nozzle 14comprises a rear section 16 and a front section 18 connected to the rearsection 16. Each section 16, 18 is annular in shape, and extends about abore 20 of the nozzle 14. The bore 20 extends centrally through thenozzle 14 so that the centre of each section 16, 18 is located on theaxis X of the bore 20.

In this example, each section 16, 18 has a “racetrack” shape, in thateach section 16, 18 comprises two, generally straight sections locatedon opposite sides of the bore 20, a curved upper section joining theupper ends of the straight sections and a curved lower section joiningthe lower ends of the straight sections. However, the sections 16, 18may have any desired shape; for example the sections 16, 18 may becircular or oval. In this embodiment, the height of the nozzle 14 isgreater than the width of the nozzle, but the nozzle 14 may beconfigured so that the width of the nozzle 14 is greater than the heightof the nozzle 14.

Each section 16, 18 of the nozzle 14 defines a flow path along which arespective one of the air flows passes. In this embodiment, the rearsection 16 of the nozzle 14 defines a first air flow path along which afirst air flow passes through the nozzle 14, and the front section 18 ofthe nozzle 14 defines a second air flow path along which a second airflow passes through the nozzle 14.

With reference also to FIG. 4( a), the rear section 16 of the nozzle 14comprises an annular first outer casing section 22 connected to andextending about an annular inner casing section 24. Each casing section22, 24 extends about the bore axis X. Each casing section may be formedfrom a plurality of connected parts, but in this embodiment each casingsection 22, 24 is formed from a respective, single moulded part. Asillustrated in FIGS. 5( a) and 5(b), a rear portion 26 of the firstouter casing section 22 is curved inwardly towards the bore axis X todefine a rear end of the nozzle 14 and a rear part of the bore 20.During assembly the end of the rear portion 26 of the first outer casingsection 22 is connected to the rear end of the inner casing section 24,for example using an adhesive. The first outer casing section 22comprises a tubular base 28 which defines a first air inlet 30 of thenozzle 14.

The front section 18 of the nozzle 14 also comprises an annular secondouter casing section 32 connected to and extending about an annularfront casing section 34. Again, each casing section 32, 34 extends aboutthe bore axis X, and may be formed from a plurality of connected parts,but in this embodiment each casing section 32, 34 is formed from arespective, single moulded part. In this example, the front casingsection 34 comprises a rear portion 36 which is connected to the frontend of the outer casing section 22, and a front portion 38 which isgenerally frusto-conical in shape and flared outwardly from the rearportion 36 away from the bore axis X. The front casing section 34 may beintegral with the inner casing section 24. The second outer casingsection 32 is generally cylindrical in shape, and extends between thefirst outer casing section 22 and the front end of the front casingsection 34. The second outer casing section 32 comprises a tubular base40 which defines a second air inlet 42 of the nozzle 14.

The casing sections 24, 34 together define a first air outlet 44 of thenozzle 14. The first air outlet 44 is defined by overlapping, or facing,surfaces of the inner casing section 24 and the rear portion 36 of thefront casing section 34 so that the first air outlet 44 is arranged toemit air from a front end of the nozzle 14. The first air outlet 44 isin the form of an annular slot, which has a relatively constant width inthe range from 0.5 to 5 mm about the bore axis X. In this example thefirst air outlet 44 has a width of around 1 mm. Where the inner casingsections 24, 34 are formed from respective components, spacers 46 may bespaced along the first air outlet 44 for urging apart the overlappingportions of the casing sections 24, 34 to control the width of the firstair outlet 44. These spacers may be integral with either of the casingsections 24, 34. Where the casing sections 24, 34 are formed from asingle component, the spacers 46 are replaced by fins which are spacedalong the first air outlet 44 for connecting together the inner casingsection 24 and the front casing section 34.

The nozzle 14 defines an annular first interior passage 48 for conveyingthe first air flow from the first air inlet 30 to the first air outlet44. The first interior passage 48 is defined by the internal surface ofthe first outer casing section 22 and the internal surface of the innercasing section 24. A tapering, annular mouth 50 guides the first airflow to the first air outlet 44. The tapering shape of the mouth 50provides for a smooth, controlled acceleration of air as it passes fromthe first interior passage 48 to the first air outlet 44. A first airflow path through the nozzle 14 may therefore be considered to be formedfrom the first air inlet 30, the first interior passage 48, the mouth 50and the first air outlet 40.

The front casing section 34 defines a plurality of second air outlets 52of the nozzle 14. The second air outlets 52 are also formed in the frontend of the nozzle 14, each on a respective side of the bore 20, forexample by moulding or machining. Each of the second air outlets 52 islocated downstream from the first air outlet 44. In this example, eachsecond air outlet 52 is in the form of a slot having a relativelyconstant width in the range from 0.5 to 5 mm. In this example eachsecond air outlet 52 has a width of around 1 mm. Alternatively, eachsecond air outlet 52 may be in the form of a row of circular aperturesor slots formed in the front casing section 34 of the nozzle 14.

The nozzle 14 defines an annular second interior passage 54 forconveying the second air flow from the second air inlet 42 to the secondair outlets 52. The second interior passage 54 is defined by theinternal surfaces of the casing sections 32, 34, and by the front partof the external surface of the first outer casing section 22. The secondinterior passage 54 is isolated within the nozzle 14 from the firstinterior passage 48. A second air flow path through the nozzle 14 maytherefore be considered to be formed by the second air inlet 42, thesecond interior passage 54 and the second air outlets 52.

Returning to FIG. 4( a) the body 12 is generally cylindrical in shape.The body 12 comprises a base 56. The base 56 has an external outer wall58 which is cylindrical in shape, and which comprises an air inlet 60.In this example, the air inlet 60 comprises a plurality of aperturesformed in the outer wall 58 of the base 56. A front portion of the base56 may comprise a user interface of the humidifying apparatus 10. Theuser interface is illustrated schematically in FIG. 13, and described inmore detail below. A mains power cable (not shown) for supplyingelectrical power to the humidifying apparatus 10 extends through anaperture formed in the base 56.

The base 56 comprises a first air passageway 62 for conveying a firstair flow to the first air flow path through the nozzle 14, and a secondair passageway 64 for conveying a second air flow to the second air flowpath through the nozzle 14.

The first air passageway 62 passes through the base 56 from the airinlet 60 to the first air inlet 30 of the nozzle 14. With reference alsoto FIGS. 6( a) and 6(b), the base 56 comprises a bottom wall 66connected to the lower end of the outer wall 58, and a generallycylindrical inner wall 68 connected to the outer wall 58 by a recessedannular wall 70. The inner wall 68 extends upwardly away from theannular wall 70. In this example, the outer wall 58, inner wall 68 andannular wall 70 are formed as a single component of the base 56, butalternatively two or more of these walls may be formed as a respectivecomponent of the base 56. An upper wall is connected to the upper end ofthe inner wall 68. The upper wall has a lower frusto-conical section 72and an upper cylindrical section 74 into which the base 28 of the nozzle14 is inserted.

The inner wall 68 extends about an impeller 76 for generating a firstair flow through the first air passageway 62. In this example theimpeller 76 is in the form of a mixed flow impeller. The impeller 76 isconnected to a rotary shaft extending outwardly from a motor 78 fordriving the impeller 76. In this embodiment, the motor 78 is a DCbrushless motor having a speed which is variable by a drive circuit 80in response to a speed selection by a user. The maximum speed of themotor 78 is preferably in the range from 5,000 to 10,000 rpm. The motor78 is housed within a motor bucket comprising an upper portion 82connected to a lower portion 84. The upper portion 82 of the motorbucket comprises a diffuser 86 in the form of a stationary disc havingcurved blades. The diffuser 86 is located beneath the first air inlet 30of the nozzle 14.

The motor bucket is located within, and mounted on, a generallyfrusto-conical impeller housing 88. The impeller housing 88 is, in turn,mounted on an annular support 90 extending inwardly from the inner wall68. An annular inlet member 92 is connected to the bottom of theimpeller housing 88 for guiding the air flow into the impeller housing88. An annular sealing member 94 is located between the impeller housing88 and the annular support 90 to prevent air from passing around theouter surface of the impeller housing 88 to the inlet member 92. Theannular support 90 preferably comprises a guide portion 96 for guidingan electrical cable from the drive circuit 80 to the motor 78. The base56 also includes a guide wall 98 for guiding air flow the air inlet 60to an air inlet port of the inlet member 92.

The first air passageway 62 extends from the air inlet 60 to the airinlet port of the inlet member 92. The first air passageway 62 extends,in turn, through the impeller housing 88, the upper end of the innerwall 68 and the sections 72, 74 of the upper wall.

An annular cavity 99 is located between the guide wall 98 and theannular wall 70. The cavity 99 has an opening which is located betweenthe inlet member 92 and the guide wall 98 so that the cavity 99 is opento the first air passageway 62. The cavity 99 contains a static pocketof air which serves to reduce the transmission of vibrations generatedduring use of the humidifying apparatus 10 to the outer surface of thebody 12.

The second air passageway 64 is arranged to receive air from the firstair passageway 62. The second air passageway 64 is located adjacent tothe first air passageway 62. The second air passageway 64 comprises aninlet duct 100. With reference to FIGS. 6( a) and 6(b), the inlet duct100 is defined by the inner wall 68 of the base 56. The inlet duct 100is located adjacent to, and in this example radially external of, partof the first air passageway 62. The inlet duct 100 extends generallyparallel to the longitudinal axis of the base 56, which is co-linearwith the rotational axis of the impeller 76. The inlet duct 100 has aninlet port 102 located downstream from, and radially outward from, thediffuser 86 so as to receive part of the air flow emitted from thediffuser 86, and which forms the second air flow. The inlet duct 100 hasan outlet port 104 located at the lower end thereof.

The second air passageway 64 further comprises an outlet duct 106 whichis arranged to convey the second air flow to the second air inlet 42 ofthe nozzle 14. The second air flow is conveyed through the inlet duct100 and the outlet duct 106 in generally opposite directions. The outletduct 106 comprises an inlet port 108 located at the lower end thereof,and an outlet port located at the upper end thereof. The base 40 of thesecond outer casing section 32 of the nozzle 14 is inserted into theoutlet port of the outlet duct 106 to receive the second air flow fromthe outlet duct 106.

The humidifying apparatus 10 is configured to increase the humidity ofthe second air flow before it enters the nozzle 14. With reference nowto FIGS. 1 to 4( a) and FIG. 7, the humidifying apparatus 10 comprises awater tank 120 removably mountable on the base 56. The base 56 and thewater tank 120 together form the body 12 of humidifying apparatus 10.The water tank 120 has a cylindrical outer wall 122 which has the sameradius as the outer wall 58 of the base 56 of the body 12 so that thebody 12 has a cylindrical appearance when the water tank 120 is mountedon the base 56. The water tank 120 has a tubular inner wall 124 whichsurrounds the walls 68, 72, 74 of the base 56 when the water tank 120 ismounted on the base 56. The outer wall 122 and the inner wall 124define, with an annular upper wall 126 and an annular lower wall 128 ofthe water tank 120, an annular volume for storing water. The water tank120 thus surrounds the impeller 76 and the motor 78, and so at leastpart of the first air passageway 62, when the water tank 120 is mountedon the base 56. The lower wall 128 of the water tank 120 engages theouter wall 58 of the base 56, and non-recessed parts of the annular wall70, when the water tank 120 is mounted on the base 56.

The water tank 120 preferably has a capacity in the range from 2 to 4litres. A window 130 is provided on the outer wall 122 of the water tank120 to allow a user to see the level of water within the water tank 120when it is disposed on the base 56.

With reference to FIG. 9, a spout 132 is removably connected to thelower wall 128 of the water tank 120, for example through co-operatingthreaded connections. In this example the water tank 120 is filled byremoving the water tank 120 from the base 56 and inverting the watertank 120 so that the spout 132 is projecting upwardly. The spout 132 isthen unscrewed from the water tank 120 and water is introduced into thewater tank 120 through an aperture exposed when the spout 132 isdisconnected from the water tank 120. Once the water tank 120 has beenfilled, the user reconnects the spout 132 to the water tank 120, returnsthe water tank 120 to its non-inverted orientation and replaces thewater tank 120 on the base 56. A spring-loaded valve 134 is locatedwithin the spout 132 for preventing leakage of water through a wateroutlet 136 of the spout 132 when the water tank 120 is re-inverted. Thevalve 134 is biased towards a position in which a skirt of the valve 134engages the upper surface of the spout 132 to prevent water entering thespout 132 from the water tank 120.

The upper wall 126 of the water tank 120 comprises one or more supports138 for supporting the inverted water tank 120 on a work surface,counter top or other support surface. In this example, two parallelsupports 138 are formed in the periphery of the upper wall 126 forsupporting the inverted water tank 120.

With reference also to FIGS. 6( a), 6(b) and 8, the outer wall 58, innerwall 68 and the recessed portion of the annular wall 70 of the base 56define a water reservoir 140 for receiving water from the water tank120. The base 56 comprises a water treatment chamber 142 for treatingwater from the water tank 120 before it enters the water reservoir 140.The water treatment chamber 142 is located to one side of the waterreservoir 140, within the recessed portion of the annular wall 70. Acover 144 connected to the annular wall 70 comprises a water inlet 146and a water outlet 148 of the water treatment chamber 142. In thisembodiment, each of the water inlet 146 and the water outlet 148comprises a plurality of apertures. Water outlet 148 is located on aninclined surface of the cover 144 so that the water outlet 148 islocated beneath the water inlet 146. The cover 144 is supported by asupporting pin 150 which extends upwardly from the annular wall 70 toengage the lower surface of the cover 144.

An upwardly extending pin 152 of the cover 144 is located betweenapertures of the water inlet 146. When the water tank 120 is mounted onthe base 56, the pin 152 protrudes into the spout 132 to push the valve134 upwardly to open the spout 132, thereby allowing water to pass undergravity through the water inlet 146 and into the water treatment chamber142. As the water treatment chamber 142 fills with water, water flowsthrough the water outlet 148 and into the water reservoir 140. The watertreatment chamber 142 houses a threshold inhibitor, such one or morebeads or pellets 154 of a polyphosphate material, which becomes added tothe water as it passes through the water treatment chamber 142.Providing the threshold inhibitor in a solid form means that thethreshold inhibitor slowly dissolves with prolonged contact with waterin the water treatment chamber 142. In view of this, the water treatmentchamber 142 comprises a barrier which prevents relatively large piecesof the threshold inhibitor from entering the water reservoir 140. Inthis example, the barrier is in the form of a wall 156 located betweenthe annular wall 70 and the water outlet 148.

Within the water reservoir 140, the annular wall 70 comprises a pair ofcircular apertures each for exposing a respective piezoelectrictransducer 160. The drive circuit 80 is configured to actuate vibrationof the transducers 160 in an atomization mode to atomise water locatedin the water reservoir 140. In the atomization mode, the transducers 160may vibrate ultrasonically at a frequency f₁, which may be in the rangefrom 1 to 2 MHz. A metallic heat sink 162 is located between the annularwall 70 and the transducers 160 for conveying heat away from thetransducers 160. Apertures 164 are formed in the bottom wall 64 of thebase 56 to dissipate heat radiated from the heat sink 162. Annularsealing members form water-tight seals between the transducers 160 andthe heat sink 162. As illustrated in FIGS. 6( a) and 6(b), theperipheral portions 166 of the apertures in the annular wall 70 areraised to present a barrier for preventing any particles of thethreshold inhibitor which have entered the water reservoir 140 from thewater treatment chamber 142 from becoming lodged on the exposed surfacesof the transducers 160.

The water reservoir 140 also includes an ultraviolet radiation (UV)generator for irradiating water stored in the water reservoir 140. Inthis example, the UV generator is in the form of a UV lamp 170 locatedwithin a UV transparent tube 172 located in the water reservoir 140 sothat, as the water reservoir 140 fills with water, water surrounds thetube 172. The tube 172 is located on the opposite side of the waterreservoir 140 to the transducers 160. One or more reflective surfaces173 may be provided adjacent to, and preferably about, the tube 172 forreflecting ultraviolet radiation emitted from the UV lamp 170 into thewater reservoir 140. The water reservoir 140 comprises baffle plates 174which guide water entering the water reservoir 140 from the watertreatment chamber 142 along the tube 172 so that, during use, the waterentering the water reservoir 140 from the water treatment chamber 142 isirradiated with ultraviolet radiation before it is atomized by one ofthe transducers 160.

A magnetic level sensor 176 is located within the water reservoir 140for detecting the level of water within the water reservoir 140.Depending on the volume of water within the water tank 120, the waterreservoir 140 and the water treatment chamber 142 can be filled withwater to a maximum level which is substantially co-planar with the uppersurface of the pin 152. The outlet port 104 of the inlet duct 100 islocated above the maximum level of water within the water reservoir 140so that the second air flow enters the water reservoir 140 over thesurface of the water located in the water reservoir 140.

The inlet port 108 of the outlet duct 106 is positioned above thetransducers 160 to receive a humidified air flow from the waterreservoir 140. The outlet duct 106 is defined by the water tank 120. Theoutlet duct 106 is formed by the inner wall 124 of the water tank 120and a curved wall 180 about which the inner wall 124 extends.

The base 56 includes a proximity sensor 182 for detecting that the watertank 120 has been mounted on the base 56. The proximity sensor 182 isillustrated schematically in FIG. 13. The proximity sensor 182 may be inthe form of a reed switch which interacts with a magnet (not shown)located on the lower wall 128 of the water tank 120 to detect thepresence, or absence, of the water tank 120 on the base 56. Asillustrated in FIGS. 7( a), 7(b) and 11, when the water tank 120 ismounted on the base 56 the inner wall 124 and the curved wall 180surround the upper wall of the base 56 to expose the open upper end ofthe upper cylindrical section 74 of the upper wall. The water tank 120includes a handle 184 to facilitate removal of the water tank 120 fromthe base 56. The handle 184 is pivotably connected to the water tank 120so as to be moveable relative to the water tank 120 between a stowedposition, in which the handle 184 is housed within a recessed section186 of the upper wall 126 of the water tank 120, and a deployedposition, in which the handle 184 is raised above the upper wall 126 ofthe water tank 120. With reference also to FIGS. 12( a) and 12(b), oneor more resilient elements 188, such as torsion springs, may be providedfor biasing the handle 184 towards its deployed position, as illustratedin FIGS. 7( a) and 7(b).

When the nozzle 14 is mounted on the body 12, the base 28 of the firstouter casing section 22 of the nozzle 14 is located over the open end ofthe upper cylindrical section 74 of the upper wall of the base 56, andthe base 40 of the second outer casing section 32 of the nozzle 14 islocated over the open upper end of the outlet duct 106 of the water tank120. The user then pushes the nozzle 14 towards the body 12. Asillustrated in FIG. 10, a pin 190 is formed on the lower surface of thefirst outer casing section 22 of the nozzle 14, immediately behind thebase 28 of the first outer casing section 22. As the nozzle 14 movestowards the body 12, the pin 190 pushes the handle 184 towards itsstowed position, against the biasing force of the resilient elements188. When the bases 28, 40 of the nozzle 14 are fully inserted in thebody 12, annular sealing members 192 form air-tight seals between theends of the bases 28, 40 and annular ledges 194 formed in the uppercylindrical section 74 of the upper wall of the base 56, and in theoutlet duct 106. The upper wall 126 of the water tank 120 has a concaveshape so that, when the nozzle 14 is mounted on the body 12, the watertank 120 surrounds a lower part of the nozzle 14. This not only can thisallow the capacity of the water tank 120 to be increased, but can alsoprovide the humidifying apparatus 10 with a compact appearance.

The body 12 comprises a mechanism for releasably retaining the nozzle 14on the body 12. FIGS. 4( a), 11 and 12(a) illustrate a firstconfiguration of the mechanism when the nozzle 14 is retained on thebody 12, whereas FIGS. 4( b) and 12(b) illustrate a second configurationof the mechanism when the nozzle 14 is released from the body 12. Themechanism for releasably retaining the nozzle 14 on the body 12comprises a pair of detents 200 which are located on diametricallyopposed sides of an annular housing 202. Each detent 200 has a generallyL-shaped cross-section. Each detent 200 is pivotably moveable between adeployed position for retaining the nozzle 14 on the body 12, and astowed position. Resilient elements 204, such as torsion springs, arelocated within the housing 202 for biasing the detents 200 towards theirdeployed positions.

In this example, the water tank 120 comprises the mechanism forreleasably retaining the nozzle 14 on the body 12. The housing 202comprises a pair of diametrically opposed apertures 206 which align withsimilarly shaped apertures 208 formed on the upper cylindrical section74 of the upper wall of the base 56 when the water tank 120 is mountedon the base 56. The outer surface of the base 28 of the nozzle 14comprises a pair of diametrically opposed recesses 210 which align withthe apertures 206, 208 when the nozzle 14 is mounted on the body 12.When the detents 200 are in their deployed position, the ends of thedetents 200 are urged through the apertures 206, 208 by the resilientelements 204 to enter the recesses 210 in the nozzle 14. The ends of thedetents 200 engage the recessed outer surface of the base 28 of thenozzle 14 to prevent the nozzle 14 from becoming withdrawn from the body12, for example if the humidifying apparatus 10 is lifted by a usergripping the nozzle 14.

The body 12 comprises a depressible catch 220 which is operable to movethe mechanism from the first configuration to the second configuration,by moving the detents 200 away from the recesses 210 to release thenozzle 14 from the body 12. The catch 220 is mounted within the housing202 for pivoting movement about an axis which is orthogonal to the axesabout which the detents 200 pivot between their stowed and deployedpositions. The catch 220 is moveable from a stowed position, asillustrated in FIGS. 4( a), 11 and 12(a), to a deployed position, asillustrated in FIGS. 4( b), 7(a), 7(b) and 12(b), in response to a userdepressing a button 222 located on the body 12. In this example, thebutton 222 is located on the upper wall 126 of the water tank 120 andabove a front section of the catch 220. A compression spring or otherresilient element may be provided beneath the front section of the catch220 for urging the catch 220 towards is stowed position. The rotationalaxis of the catch 220 is located proximate to the front section of thecatch so that, as the catch 220 moves towards its deployed position, thecatch 220 urges the detents 200 to pivot away from the recesses 210against the biasing force of the resilient elements 204.

The body 12 is configured to retain the catch 220 in its deployedposition when the user releases the button 220. In this example, thehousing 202 of the water tank 120 comprises a wedge 224 over which ahook 226 located on the rear section of the catch 220 slides as thecatch 220 moves towards its deployed position. In the deployed position,the end of the hook 226 snaps over the tapered side surface of the wedge224 to engage the upper surface of the wedge 224, resulting in the catch220 being retained in its deployed position. As the hook 226 moves overthe upper surface of the wedge 224, the hook 226 engages the bottom ofthe handle 184 and urges the handle 184 upwardly away from the recessedsection 186 of the water tank 120. This in turn causes the handle 184 topush the nozzle 14 slightly away from the body 12, providing a visualindication to the user that the nozzle 14 has been released from thebody 12. As an alternative to having features on the water tank 120 andthe catch 220 which co-operate to retain the catch 220 in its deployedposition, one or more magnets may be used to retain the catch 220 in itsdeployed position.

In its deployed position, the catch 220 holds the detents 200 in theirstowed positions, as illustrated in FIGS. 4( b) and 12(b), to allow theuser to remove the nozzle 14 from the body 12. As the nozzle 14 islifted from the body 12, the resilient elements 188 urge the handle 184to its deployed position. The user can then use the handle 184 to liftthe water tank 120 from the base 56 to allow the water tank 120 to befilled or cleaned as required.

Once the water tank 120 has been filled or cleaned, the user replacesthe water tank 120 on the base 56, and then replaces the nozzle 14 onthe body 12. As the bases 28, 40 of the nozzle 14 are pushed into thebody 12 the pin 190 on the nozzle 14 engages the handle 184 and pushesthe handle 184 back to its stowed position within the recessed section186 of the water tank 120. As the handle 184 moves to its stowedposition, it engages the hook 226 on the catch 220 and pushes the hook226 away from the upper surface of the wedge 224 to release the catch220 from its deployed position. As the hook 226 moves away from thewedge 224, the resilient elements 204 urge the detents 200 towards theirdeployed positions to retain the nozzle 14 on the body 12. As thedetents 200 move towards their deployed position, the detents 200 movethe catch 220 back to its stowed position.

A user interface for controlling the operation of the humidifyingapparatus is located on the outer wall 58 of the base 56 of the body 12.FIG. 13 illustrates schematically a control system for the humidifyingapparatus 10, which includes this user interface and other electricalcomponents of the humidifying apparatus 10. In this example, the userinterface comprises a plurality of user-operable buttons 240 a, 240 band 240 c, and a display 242. The first button 240 a is used to activateand deactivate the motor 78, and the second button 240 b is used to setthe speed of the motor 78, and thus the rotational speed of the impeller76. The third button 240 c is used to set a desired level for therelative humidity of the environment in which the humidifying apparatus10 is located, such as a room, office or other domestic environment. Forexample, the desired relative humidity level may be selected within arange from 30 to 80% at 20° C. through repeated actuation of the thirdbutton 240 c. The display 242 provides an indication of the currentlyselected relative humidity level.

The user interface further comprises a user interface circuit 244 whichoutputs control signals to the drive circuit 80 upon actuation of one ofthe buttons, and which receives control signals output by the drivecircuit 80. The user interface may also comprise one or more LEDs forproviding a visual alert depending on a status of the humidifyingapparatus. For example, a first LED 246 a may be illuminated by thedrive circuit 80 indicating that the water tank 120 has become depleted,as indicated by a signal received by the drive circuit 80 from the levelsensor 176.

A humidity sensor 248 is also provided for detecting the relativehumidity of air in the external environment, and for supplying a signalindicative of the detected relative humidity to the drive circuit 80. Inthis example the humidity sensor 248 may be located immediately behindthe air inlet 60 to detect the relative humidity of the air flow drawninto the humidifying apparatus 10. The user interface may comprise asecond LED 246 b which is illuminated by the drive circuit 80 when anoutput from the humidity sensor 248 indicates that the relative humidityof the air flow entering the humidifying apparatus 10, H_(D), is at orabove the desired relative humidity level, H_(S), set by the user.

With reference also to FIG. 14, to operate the humidifying apparatus 10,the user actuates the first button 240 a. The operation of the button240 a is communicated to the drive circuit 80, in response to which thedrive circuit 80 actuates the UV lamp 170 to irradiate water stored inthe water reservoir 140. In this example, the drive circuit 80simultaneously activates the motor 78 to rotate the impeller 76. Therotation of the impeller 76 causes air to be drawn into the body 12through the air inlet 60. An air flow passes through the impellerhousing 88 and the diffuser 86. Downstream from the diffuser 86, aportion of the air emitted from the diffuser 86 enters the inlet duct100 through the inlet port 102, whereas the remainder of the air emittedfrom the diffuser 86 is conveyed along the first air passageway 62 tothe first air inlet 30 of the nozzle 14. The impeller 76 and the motor78 may thus be considered to generate a first air flow which is conveyedto the nozzle 14 by the first air passageway 62 and which enters thenozzle 14 through the first air inlet 30.

The first air flow enters the first interior passage 48 at the base ofthe rear section 16 of the nozzle 14. At the base of the first interiorpassage 48, the air flow is divided into two air streams which pass inopposite directions around the bore 20 of the nozzle 14. As the airstreams pass through the first interior passage 48, air enters the mouth50 of the nozzle 14. The air flow into the mouth 50 is preferablysubstantially even about the bore 20 of the nozzle 14. The mouth 50guides the air flow towards the first air outlet 44 of the nozzle 14,from where it is emitted from the humidifying apparatus 10.

The air flow emitted from the first air outlet 40 causes a secondary airflow to be generated by the entrainment of air from the externalenvironment, specifically from the region around the first air outlet 44and from around the rear of the nozzle 14. Some of this secondary airflow passes through the bore 20 of the nozzle 14, whereas the remainderof the secondary air flow becomes entrained within the air flow emittedfrom the first air outlet in front of the nozzle 14.

As mentioned above, with rotation of the impeller 76 air enters thesecond air passageway 64 through the inlet port 102 of the inlet duct100 to form a second air flow. The second air flow passes through theinlet duct 100 and is emitted through the outlet port 104 over the waterstored in the water reservoir 140. The emission of the second air flowfrom the outlet port 104 agitates the water stored in the waterreservoir 140 to generate movement of water along and around the UV lamp170, increasing the volume of water which is irradiated by the UV lamp170. The presence of the threshold inhibitor within the stored watercauses a thin layer of the threshold inhibitor to be formed on thesurfaces of the tube 172 and the transducers 160 which are exposed tothe stored water, inhibiting the precipitation of limescale on thosesurfaces. This can both prolong the working life of the transducers 160and inhibit any degradation in the illumination of the stored water bythe UV lamp 170.

In addition to the agitation of the water stored in the water reservoir140 by the second air flow, the agitation may also be performed by thevibration of the transducers 160 in an agitation mode which isinsufficient to cause atomization of the stored water. Depending, forexample on the size and the number of transducers 160 of the base 56,the agitation of the stored water may be performed solely by vibrationof the transducers 160 at a reduced second frequency f₂, and/or at areduced amplitude, or with a different duty cycle. In this case, thedrive circuit 80 may be configured to actuate the vibration of thetransducers 160 in this agitation mode simultaneously with theirradiation of the stored water by the UV lamp 170.

The agitation and irradiation of the stored water continues for a periodof time sufficient to reduce the level of bacteria within the waterreservoir 140 by a desired amount. In this example, the water reservoir140 has a maximum capacity of 200 ml, and the agitation and irradiationof the stored water continues for a period of 60 seconds beforeatomization of the stored water commences. The duration of this periodof time may be lengthened or shortened depending on, for example, thedegree of agitation of the stored water, the capacity of the waterreservoir 140, and the intensity of the irradiation of the stored water,and so depending on these variables the duration of this period of timemay take any value in the range of 10 to 300 seconds to achieve thedesired reduction in the number of bacteria within the stored water.

At the end of this period of time, the drive circuit 80 actuates thevibration of the transducers 160 in the atomization mode to atomizewater stored in the water reservoir 140. This creates airborne waterdroplets above the water located within the water reservoir 140. In theevent that the stored water was agitated previously by vibration of thetransducers 160 alone, the motor 78 is also activated at this end ofthis period of time.

As water within the water reservoir 140 is atomized, the water reservoir140 is constantly replenished with water received from the water tank120 via the water treatment chamber 142, so that the level of waterwithin the water reservoir 140 remains substantially constant while thelevel of water within the water tank 120 gradually falls. As waterenters the water reservoir 140 from the water treatment chamber 142, inwhich the threshold inhibitor is added to the water, it is guided by thewalls 174 to flow along the tube 172 so that it is irradiated withultraviolet radiation before it is atomized.

With rotation of the impeller 76, airborne water droplets becomeentrained within the second air flow emitted from the outlet port 104 ofthe inlet duct 100. The—now moist—second air flow passes upwardlythrough the outlet duct 106 of the second air passageway 64 to thesecond air inlet 42 of the nozzle 14, and enters the second interiorpassage 54 within the front section 18 of the nozzle 14.

At the base of the second interior passage 54, the second air flow isdivided into two air streams which pass in opposite directions aroundthe bore 20 of the nozzle 14. As the air streams pass through the secondinterior passage 54, each air stream is emitted from a respective one ofthe second air outlets 52 located in the front end of the nozzle 14 infront of the first air outlet 44. The emitted second air flow isconveyed away from the humidifying apparatus 10 within the air flowgenerated through the emission of the first air flow from the nozzle 14,thereby enabling a humid air current to be experienced rapidly at adistance of several metres from the humidifying apparatus 10.

The moist air flow is emitted from the nozzle 14 until the relativehumidity H_(D) of the air flow entering the humidifying apparatus 10, asdetected by the humidity sensor 248, is 1% at 20° C. higher than therelative humidity level H_(S), selected by the user using the thirdbutton 240 c. The emission of the moistened air flow from the nozzle 14may then be terminated by the drive circuit 80, preferably by changingthe mode of vibration of the transducers 160. For example, the frequencyof the vibration of the transducers 160 may be reduced to a frequencyf₃, where f₁>f₃≧0, below which atomization of the stored water is notperformed. Alternatively the amplitude of the vibrations of thetransducers 160 may be reduced. Optionally, the motor 78 may also bestopped so that no air flow is emitted from the nozzle 14. However, whenthe humidity sensor 248 is located in close proximity to the motor 78 itis preferred that the motor 78 is operated continually to avoidundesirable temperature fluctuation in the local environment of thehumidity sensor 248. Also, it is preferred to continue to operate themotor 78 to continue agitating the water stored in the water reservoir140. Operation of the UV lamp 170 is also continued.

As a result of the termination of the emission of a moist air flow fromthe humidifying apparatus 10, the relative humidity H_(D) detected bythe humidity sensor 248 will begin to fall. Once the relative humidityof the air of the environment local to the humidity sensor 248 hasfallen to 1% at 20° C. below the relative humidity level H_(S) selectedby the user, the drive circuit 80 re-activates the vibration of thetransducers 160 in the atomization mode. If the motor 78 has beenstopped, the drive circuit 80 simultaneously re-activates the motor 78.As before, the moist air flow is emitted from the nozzle 14 until therelative humidity H_(D) detected by the humidity sensor 248 is 1% at 20°C. higher than the relative humidity level H_(S) selected by the user.

This actuation sequence of the transducers 160 (and optionally the motor78) for maintaining the detected humidity level around the levelselected by the user continues until button 240 a is actuated again, oruntil a signal is received from the level sensor 176 indicating that thelevel of water within the water reservoir 140 has fallen below theminimum level. If the button 240 a is actuated, or upon receipt of thissignal from the level sensor 176, the drive circuit 80 deactivates themotor 78, the transducers 160 and the UV lamp 170 to switch off thehumidifying apparatus 10. The drive circuit 80 also deactivates thesecomponents of the humidifying apparatus 10 in response to signalreceived from the proximity sensor 182 indicating that the water tank120 has been removed from the base 56.

1. A humidifying apparatus comprising: a housing comprising a waterreservoir; a water tank mounted on the housing for supplying water tothe reservoir; an air flow generating device for generating an air flowover water in the reservoir; an air outlet for emitting at least part ofthe air flow: an atomizing device for atomizing water in the reservoir;an ultraviolet radiation irradiating device for irradiating water in thereservoir with ultraviolet radiation; and at least one guide member forguiding a flow of water entering the reservoir adjacent to theirradiating device.
 2. The apparatus of claim 1, wherein the at leastone guide member comprises at least one baffle.
 3. The apparatus ofclaim 1, wherein the at least one guide member is located adjacent tothe irradiating device.
 4. The apparatus of claim 1, comprising achamber for conveying water from the water tank to the reservoir, andwherein the at least one guide member is located adjacent to a wateroutlet of the chamber.
 5. The apparatus of claim 1, wherein theirradiating device is located at least partially within the reservoir.6. The apparatus of claim 5, wherein the irradiating device comprises anultraviolet radiation transparent tube located at least partially withinthe reservoir.
 7. The apparatus of claim 6, wherein the at least oneguide member is arranged to guide water entering the reservoir along thetube.
 8. The apparatus of claim 1, wherein the atomizing devicecomprises a transducer, and the apparatus comprises a controller forcontrolling the frequency of vibration of the transducer.
 9. Theapparatus of claim 8, wherein the transducer is located on the oppositeside of the reservoir to the irradiating device.
 10. The apparatus ofclaim 1, comprising an inlet duct for conveying the air flow to thereservoir, and an outlet duct for conveying the air flow away from thereservoir.
 11. The apparatus of claim 10, wherein the inlet ductcomprises an outlet port shaped to emit the air flow in such a directionas to generate a swirling movement of the water stored in the reservoir.12. The apparatus of claim 10, wherein the inlet duct extends along atleast part of the outlet duct.
 13. The apparatus of claim 10, whereinthe housing comprises the inlet duct, and the water tank comprises theoutlet duct.
 14. The apparatus of claim 1, comprising a nozzle forreceiving the air flow, the nozzle comprising said air outlet, thenozzle extending about an opening through which air from outside theapparatus is drawn by air emitted from the nozzle.